The present invention relates to a tool which is used to apply a torque to a nut, bolt, screw or the like for purposes of installing or removing the nut, bolt screw, or other parts situated in places inaccessible to ordinary hand tools. The device of the invention is especially useful in conjunction with the assembly or repair of airplanes or motor vehicles or in any location which is restricted in access to conventional socket wrench sets, screwdrivers, and adjustable wrenches.
Several devices have been proposed for providing a remote driver to apply torque to a nut or bolt through a gear train or chain. U.S. Pat. No. 4,374,480 to Diaz teaches an extension wrench for transmitting a torque to a fastener. The extension wrench comprises an elongated frame, housing a driven gear at one end, a driving gear at the opposite end and a meshing gear train between the driving gear and driven gears which transmits torque from the driving gear to the driven gear. The gears have no shafts for support but instead, each gear is inserted into a closely fitting circular recess in the elongated frame. By this design, the peripheral edge of each gear bears against the close fitting circular recess. The consequence of this gear recess arrangement is that clearances must be provided between the ends of the teeth of the gear and the recess. This allows the gear to move slightly, thereby, bearing unevenly against the recess wall. Further, the misalignment of these gears causes a shift of the entire load to one edge of the tooth with resulting excessive stress being created.
U.S. Pat. No. 4,374,479 to Minotti teaches a tool for transmitting torque from a driving member to a work piece and comprises a plurality of serially engaging gears. In Minotti, gears bear both on central shafts, about which each gear rotates, and also on a coaxial cylindrical shoulder extending outwardly from opposites sides of otherwise flat generally circular surfaces of the gears. A housing having an upper part, and a lower part each with a recess for receiving the shoulder portion, includes holes to receive the central shaft about which the gears rotate. A major drawback of the tool taught by Minotti is that the frame or housing supporting the gear frame is open, thereby allowing dirt or metal chips to enter the gear train and aggravate wear and breakage of the gear system. Further, bolting down the housing parts of Minotti increases the sliding friction at the bearing surface of the gears, thereby causing the device to be inefficient.